For light emitting devices, such as light emitting diodes (LED), the emission wavelength is determined by the band gap of the active region of the LED together with thickness determined confinement effects. Often the active region includes one or more bulk semiconductor layers or quantum wells (QWs). For III-nitride based LED devices, such as GaN based devices, the active region (e.g., bulk semiconductor layer or QW well layer) material is preferably ternary, such as InxGa1-xN, where 0<x<1.
The band gap of such III-nitride is dependent on the amount of In incorporated in the active region. Higher indium incorporation will yield a smaller band gap and thus longer wavelength of the emitted light. As used herein, the term “wavelength” refers to the peak emission wavelength of the LED. It should be understood that a typical emission spectra of a semiconductor LED is a narrow band of wavelength centered around the peak wavelength.
Multi-color LED arrays in the prior art suffer from several drawbacks. Some multi-color LEDs form nanowire LEDs which emit different color light (i.e., different wavelength) from different portions of the same nanowire, which makes it difficult to control and selectively activate the different emission wavelengths from the same nanowire LED.